A new approach for synthesizing Ge quantum crystallites embedded in a‐SiNx films

In this letter, we present a new approach for synthesizing Ge quantum crystallites embedded in a‐SiNx films. On the basis of preferential chemical bonding formation of Si‐N and Ge‐Ge, thin films with Ge clusters embedded in a‐SiNx matrix have been prepared by the plasma enhanced chemical vapor deposition method with reactant gases of SiH4, GeH4 and NH3 mixed in hydrogen plasma at substrate temperature of 250 °C. Then the as‐deposited films were annealed at 800 °C for 30 min in the vacuum for the crystallization of Ge clusters and the growth of nanometer‐sized Ge quantum crystallites. These samples were characterized by infrared absorption spectra, transmission electron microscopy, x‐ray diffraction, and Raman scattering spectra. The average size of Ge crystallites was found to be about 200 A. By choosing conditions of the deposition and thermal‐annealing treatment, the size of Ge quantum crystallites can be prepared in a controlled manner.